In the fictional Great Qian Dynasty, the eldest princess Nan Li was separated from the imperial family during a palace coup when she was young and ended up living among commoners, making a living by slaughtering pigs. For five years, she devoted all her financial resources to supporting the scholar Zhao Xun. After Zhao Xun passed the imperial examinations and became the top scholar, he repaid her kindness with betrayal, looking down on her and the beggar parents who had finally found her, while desperately seeking to attach himself to the noblewoman Qian Ling'er. Unbeknownst to him, the beggars were actually the Emperor and Empress, who had disguised themselves to search for their daughter. Moved by Nan Li's filial devotion to her parents, they revealed their identities on the spot and bestowed upon her the title of Princess Who Guards the Nation. Later, the ambitious Prince of Han launched a rebellion and imprisoned the Emperor and Empress. With the help of the loyal general Wang En, Nan Li retrieved the military weapons secretly hidden by the late emperor, led her troops to crush the rebellion, and brought Zhao Xun and his fellow traitors to justice. In the end, she ascended the throne and became a great female emperor.